1. Technical Field
The invention relates to a method for providing a subscriber with information relating to call-charges for telecommunication services associated with a communication link, a call-charge device, a subscriber terminal for connection to a communication network, and a service unit of a communication network.
2. Discussion of Related Art
The conventional method of charging for telecommunication services in telephone networks is described, for example, in chapter "3.4.1 Secondary Exchange" in the book "Fundamentals of telephone switching engineering", by Gerd Siegmund, published by R. v. Decker Verlag, G. Schenk, 1991, pages 93 to 94.
During the call set-up phase, the tariff zone of the communication link to be set up is determined and a metering pulse generator is configured accordingly. As long as the communication link is operative, metering pulses are transmitted by the metering pulse generator via the two-wire line of the voice channel. The pulse repetition rate of the metering pulse generator corresponds to the tariff zone determined when the connection was set up, wherein each metering pulse is representative of one charge unit charged for using the telecommunication service, in this case the voice connection.
The metering pulses can also be provided to the calling subscriber terminal via the two-wire line in the voice circuit. By evaluating the number of the received metering pulses, the terminal can then calculate the charges which were actually incurred for the communication link, and display these charges to the subscriber by way of a call-charge display.
This solution, however, has the disadvantage that the display displaying the calculated charges cannot be monitored continuously during the call. For example, in many terminals the display is integrated with the handset. Consequently, the incurred charges can only be determined at the end of a call. It is thus not possible to monitor and influence these charges.